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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.solr.search;

import java.io.IOException;
import java.util.Arrays;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.CollectionTerminatedException;
import org.apache.lucene.search.Collector;
import org.apache.lucene.search.FilterCollector;
import org.apache.lucene.search.FilterLeafCollector;
import org.apache.lucene.search.LeafCollector;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.SortField;
import org.apache.lucene.search.TopDocsCollector;
import org.apache.lucene.search.TopFieldCollector;
import org.apache.lucene.search.TotalHitCountCollector;

/**
 * A {@link Collector} that early terminates collection of documents on a per-segment basis, if the
 * segment was sorted according to the given {@link Sort}.
 *
 * 

NOTE: the {@code Collector} detects segments sorted according to a an {@link * IndexWriterConfig#setIndexSort}. Also, it collects up to a specified {@code numDocsToCollect} * from each segment, and therefore is mostly suitable for use in conjunction with collectors such * as {@link TopDocsCollector}, and not e.g. {@link TotalHitCountCollector}. * *

NOTE: If you wrap a {@code TopDocsCollector} that sorts in the same order as the index * order, the returned {@link TopDocsCollector#topDocs() TopDocs} will be correct. However the total * of {@link TopDocsCollector#getTotalHits() hit count} will be vastly underestimated since not all * matching documents will have been collected. * * @deprecated Use {@link TopFieldCollector} and set trackTotalHits to false. * @lucene.experimental */ @Deprecated final class EarlyTerminatingSortingCollector extends FilterCollector { /** * Returns whether collection can be early-terminated if it sorts with the provided {@link Sort} * and if segments are merged with the provided {@link Sort}. */ public static boolean canEarlyTerminate(Sort searchSort, Sort mergePolicySort) { final SortField[] fields1 = searchSort.getSort(); final SortField[] fields2 = mergePolicySort.getSort(); // early termination is possible if fields1 is a prefix of fields2 if (fields1.length > fields2.length) { return false; } return Arrays.asList(fields1).equals(Arrays.asList(fields2).subList(0, fields1.length)); } /** Sort used to sort the search results */ private final Sort sort; /** Number of documents to collect in each segment */ private final int numDocsToCollect; private final AtomicBoolean terminatedEarly = new AtomicBoolean(false); /** * Create a new {@link EarlyTerminatingSortingCollector} instance. * * @param in the collector to wrap * @param sort the sort you are sorting the search results on * @param numDocsToCollect the number of documents to collect on each segment. When wrapping a * {@link TopDocsCollector}, this number should be the number of hits. * @throws IllegalArgumentException if the sort order doesn't allow for early termination with the * given merge policy. */ public EarlyTerminatingSortingCollector(Collector in, Sort sort, int numDocsToCollect) { super(in); if (numDocsToCollect <= 0) { throw new IllegalArgumentException( "numDocsToCollect must always be > 0, got " + numDocsToCollect); } this.sort = sort; this.numDocsToCollect = numDocsToCollect; } @Override public LeafCollector getLeafCollector(LeafReaderContext context) throws IOException { Sort segmentSort = context.reader().getMetaData().getSort(); if (segmentSort != null && canEarlyTerminate(sort, segmentSort) == false) { throw new IllegalStateException( "Cannot early terminate with sort order " + sort + " if segments are sorted with " + segmentSort); } if (segmentSort != null) { // segment is sorted, can early-terminate return new FilterLeafCollector(super.getLeafCollector(context)) { private int numCollected; @Override public void collect(int doc) throws IOException { super.collect(doc); if (++numCollected >= numDocsToCollect) { terminatedEarly.set(true); throw new CollectionTerminatedException(); } } }; } else { return super.getLeafCollector(context); } } public boolean terminatedEarly() { return terminatedEarly.get(); } }





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